TypeScript starter API templates fail tsc due to .ts import extension

## Problem

The TypeScript starter API templates import `instrumentation.ts` with an explicit `.ts` extension, but the template API `tsconfig.json` does not enable `allowImportingTsExtensions`. A plain TypeScript compile therefore fails with `TS5097`.

The generated app can still run through the current `npm start` path because it uses `tsx`, but the template source does not type-check with `tsc` as written.

cc @IEvangelist

## Repro

From the repo root:

```bash
cd src/Aspire.Cli/Templating/Templates/ts-starter/api
npm install
npm exec --yes --package typescript -- tsc -p tsconfig.json --noEmit
```

Expected: the template API TypeScript source type-checks successfully.

Actual:

```text
src/index.ts:6:8 - error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.

6 import "./instrumentation.ts";
~~~~~~~~~~~~~~~~~~~~~~
```

The same repro applies to:

```bash
cd src/Aspire.Cli/Templating/Templates/java-starter/api
npm install
npm exec --yes --package typescript -- tsc -p tsconfig.json --noEmit
```

and to the playground app:

```bash
cd playground/JavaAppHost/api
npm install
npm exec --yes --package typescript -- tsc -p tsconfig.json --noEmit
```

## Source files with the problematic import

Each file imports `./instrumentation.ts` from `src/index.ts`:

- `src/Aspire.Cli/Templating/Templates/ts-starter/api/src/index.ts`
- `src/Aspire.Cli/Templating/Templates/java-starter/api/src/index.ts`
- `playground/JavaAppHost/api/src/index.ts`

## Notes

The import currently looks like this:

```ts
import "./instrumentation.ts";
```

A likely fix is to make the import and TypeScript configuration agree, for example by removing the `.ts` extension from the import or by explicitly enabling compatible TypeScript compiler settings if keeping extensionful TypeScript imports is intentional.